This invention relates generally to an improved method employing an ion exchange resin, and in one embodiment to the use of a fluidized resin bed in combination with a high kinetic resin in an upward liquid service flow. In another embodiment, it is directed to partial salting or proportional regeneration of a resin bed.
Various methods have been employed in liquid treatment with an ion exchange resin. A common approach in using water as the treated liquid is that indicated in U.S. Pat. No. 4,737,275 which is commonly assigned and shows downward flow for service and regeneration. In that patent, raw water is introduced at the top of the resin bed and the treated water is removed from the bottom. Upward water treatment flow in a resin bed is also known. For example, in an article entitled "New Developments in Counter-Current Fixed Ion Exchange" by I. M. Abrams appearing in the 34th International Water Conference (1973), a partially fluidized bed is described with an upward service flow of the water. However, this article, as does many others, teaches that a fully fluidized bed operation is not to be employed and accordingly uses a fluidized bed in one portion and a fixed bed in another. One reason a completely fluidized resin bed is contra-indicated is that it can produce voids in the resin bed and therefore water could pass through the resin bed without being treated. An apparatus for preventing such voids and effecting a compact resin bed is disclosed in U.S. Pat. No. 4,337,153.
In a paper published at the 39th annual meeting of the International Water Conference in Pittsburgh, Pa. (Oct. 31, Nov. 1,2-1978) by F. Martinola IWC-78-5 entitled "The Lewatit-WS-Process a Highly Reliable Counter-Current System For Ion Exchange And Adsorption", the well known counter-current operation of an ion exchange resin bed was discussed. As stated in that paper, in most of the counter-current processes, the mass of resin is kept in a compressed position in the exhaustion phase as well as in the regeneration phase. However, one process is described which utilizes a totally fluidized bed in the exhaustion phase. A publication is referred to which is Wofatit-Information, DDR, Wofatit KPS, KPS-AS, (Aug., 1978). However, there is no description of the use of high kinetic resins so that an efficient fluidized bed procedure can be effected.
Partial salting or proportional regeneration of a resin bed is described in U.S. Pat. Nos. 3,048,274 and 4,379,057. However, there is no teaching of cocurrent service flow and regeneration with monospheric resins.